Unable to obtain a DHCP lease on NFS vmkernel interface
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Unable to obtain a DHCP lease on NFS vmkernel interface

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Article ID: 399131

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Updated On:

Products

VMware vSphere ESXi

Issue/Introduction

  • When a VMkernel interface has acquired its IP lease from a DHCP server in another subnet, you may see messages in the /var/log/dhclient.log file similar to:

YYYY-MM-DDTHH:MM:SS.SSSSZ dhclient-uw[2098145]: DHCPREQUEST on vmk# to <DHCP_SERVER_IP> port 67
YYYY-MM-DDTHH:MM:SS.SSSSZ dhclient-uw[2098145]: DHCPREQUEST on vmk# to <DHCP_SERVER_IP> port 67
YYYY-MM-DDTHH:MM:SS.SSSSZ dhclient-uw[2098145]: DHCPREQUEST on vmk# to <DHCP_SERVER_IP> port 67
YYYY-MM-DDTHH:MM:SS.SSSSZ dhclient-uw[2098145]: DHCPREQUEST on vmk# to <DHCP_SERVER_IP> port 67
YYYY-MM-DDTHH:MM:SS.SSSSZ dhclient-uw[2098145]: DHCPREQUEST on vmk# to <DHCP_SERVER_IP> port 67
YYYY-MM-DDTHH:MM:SS.SSSSZ dhclient-uw[2098145]: DHCPREQUEST on vmk# to <DHCP_SERVER_IP> port 67
YYYY-MM-DDTHH:MM:SS.SSSSZ dhclient-uw[2098145]: DHCPREQUEST on vmk# to <DHCP_SERVER_IP> port 67
YYYY-MM-DDTHH:MM:SS.SSSSZ dhclient-uw[2098145]: DHCPREQUEST on vmk# to <DHCP_SERVER_IP> port 67
YYYY-MM-DDTHH:MM:SS.SSSSZ dhclient-uw[2098145]: DHCPREQUEST on vmk# to <DHCP_SERVER_IP> port 67
YYYY-MM-DDTHH:MM:SS.SSSSZ dhclient-uw[2098145]: DHCPREQUEST on vmk# to <DHCP_SERVER_IP> port 67
YYYY-MM-DDTHH:MM:SS.SSSSZ dhclient-uw[2098145]: DHCPREQUEST on vmk# to <DHCP_SERVER_IP> port 67
YYYY-MM-DDTHH:MM:SS.SSSSZ dhclient-uw[2098145]: DHCPREQUEST on vmk# to <DHCP_SERVER_IP> port 67
YYYY-MM-DDTHH:MM:SS.SSSSZ dhclient-uw[2098145]: DHCPREQUEST on vmk# to <DHCP_SERVER_IP> port 67
YYYY-MM-DDTHH:MM:SS.SSSSZ dhclient-uw[2098145]: DHCPREQUEST on vmk# to <DHCP_SERVER_IP> port 67

  • An outage affected the remote sites, and the DHCP servers were located in the main datacenter. After the outage, the NFS VMkernel interface did not recover, which caused the storage to become inaccessible.

Environment

VMware vSphere ESXi

Cause

  • The VMkernel client interface sends a DHCPDiscover (broadcast) to find available DHCP servers and request an IP address.
  • The DHCP server responds with a DHCPOffer (unicast) offering an IP to the client.
  • At time T1 (default = 0.5 × lease duration), the client enters the RENEWING state and sends a DHCPREQUEST (unicast) to extend its lease.
  • This renewal request is logged in /var/log/dhclient.log (as shown in the issue section).
  • The outage occurred right before the lease renewal time.
  • Since the lease duration was 2 hours, the hosts had only a few minutes left before renewal.

 

  • Example:

Duration: ~1 hour 59 minutes.

The issue occurred just before lease expiry, leading to the host becoming disconnected.

Resolution

  • There was a 2-hour DHCP reservation in place.
  • The DHCP request was sent immediately after the network outage occurred.
  • The outage was resolved shortly after the lease expiration period.
  • Recommendation: Configure longer lease durations on the DHCP server to avoid similar issues.
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